Enable FLEX_BG feature support

Add FLEX_BG as a supported feature bit.

Add support to mke2fs to create filesystems with FLEX_BG.

Add support to tune2fs to add (and remove, if it won't break
filesystem consistency) the FLEX_BG feature.
Signed-off-by: Jose R. Santos <jrs@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
--

 lib/e2p/feature.c   |    2 ++
 lib/ext2fs/ext2fs.h |    6 ++++--
 misc/mke2fs.c       |    7 ++++++-
 3 files changed, 12 insertions(+), 3 deletions(-)

lib/e2p/feature.c

@@ -67,6 +67,8 @@ static struct feature feature_list[] = {
 			"extent" },
 	{	E2P_FEATURE_INCOMPAT, EXT4_FEATURE_INCOMPAT_64BIT,
 			"64bit" },
+	{       E2P_FEATURE_INCOMPAT, EXT4_FEATURE_INCOMPAT_FLEX_BG,
+                        "flex_bg"},
 	{	0, 0, 0 },
 };
 

lib/ext2fs/ext2fs.h

@@ -433,12 +433,14 @@ typedef struct ext2_icount *ext2_icount_t;
 					 EXT2_FEATURE_INCOMPAT_COMPRESSION|\
 					 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV|\
 					 EXT2_FEATURE_INCOMPAT_META_BG|\
-					 EXT3_FEATURE_INCOMPAT_RECOVER)
+					 EXT3_FEATURE_INCOMPAT_RECOVER|\
+					 EXT4_FEATURE_INCOMPAT_FLEX_BG)
 #else
 #define EXT2_LIB_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE|\
 					 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV|\
 					 EXT2_FEATURE_INCOMPAT_META_BG|\
-					 EXT3_FEATURE_INCOMPAT_RECOVER)
+					 EXT3_FEATURE_INCOMPAT_RECOVER|\
+					 EXT4_FEATURE_INCOMPAT_FLEX_BG)
 #endif
 #define EXT2_LIB_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER|\
 					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE)

misc/mke2fs.c

@@ -872,7 +872,8 @@ static __u32 ok_features[3] = {
 		EXT2_FEATURE_COMPAT_LAZY_BG,	/* Compat */
 	EXT2_FEATURE_INCOMPAT_FILETYPE|		/* Incompat */
 		EXT3_FEATURE_INCOMPAT_JOURNAL_DEV|
-		EXT2_FEATURE_INCOMPAT_META_BG,
+		EXT2_FEATURE_INCOMPAT_META_BG|
+		EXT4_FEATURE_INCOMPAT_FLEX_BG,
 	EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER	/* R/O compat */
 };
 

misc/tune2fs.c

@@ -97,7 +97,8 @@ static void usage(void)
 static __u32 ok_features[3] = {
 	EXT3_FEATURE_COMPAT_HAS_JOURNAL |
 		EXT2_FEATURE_COMPAT_DIR_INDEX,	/* Compat */
-	EXT2_FEATURE_INCOMPAT_FILETYPE,		/* Incompat */
+	EXT2_FEATURE_INCOMPAT_FILETYPE|		/* Incompat */
+		EXT4_FEATURE_INCOMPAT_FLEX_BG,
 	EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER	/* R/O compat */
 };
 
@@ -283,6 +284,7 @@ static void update_feature_set(ext2_filsys fs, char *features)
 {
 	int sparse, old_sparse, filetype, old_filetype;
 	int journal, old_journal, dxdir, old_dxdir;
+	int flex_bg, old_flex_bg;
 	struct ext2_super_block *sb= fs->super;
 	__u32	old_compat, old_incompat, old_ro_compat;
 
@@ -294,6 +296,8 @@ static void update_feature_set(ext2_filsys fs, char *features)
 		EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER;
 	old_filetype = sb->s_feature_incompat &
 		EXT2_FEATURE_INCOMPAT_FILETYPE;
+	old_flex_bg = sb->s_feature_incompat &
+		EXT4_FEATURE_INCOMPAT_FLEX_BG;
 	old_journal = sb->s_feature_compat &
 		EXT3_FEATURE_COMPAT_HAS_JOURNAL;
 	old_dxdir = sb->s_feature_compat &
@@ -308,6 +312,8 @@ static void update_feature_set(ext2_filsys fs, char *features)
 		EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER;
 	filetype = sb->s_feature_incompat &
 		EXT2_FEATURE_INCOMPAT_FILETYPE;
+	flex_bg = sb->s_feature_incompat &
+		EXT4_FEATURE_INCOMPAT_FLEX_BG;
 	journal = sb->s_feature_compat &
 		EXT3_FEATURE_COMPAT_HAS_JOURNAL;
 	dxdir = sb->s_feature_compat &
@@ -352,6 +358,14 @@ static void update_feature_set(ext2_filsys fs, char *features)
 		if (uuid_is_null((unsigned char *) sb->s_hash_seed))
 			uuid_generate((unsigned char *) sb->s_hash_seed);
 	}
+	if (!flex_bg && old_flex_bg) {
+		if (ext2fs_check_desc(fs)) {
+			fputs(_("Clearing the flex_bg flag would "
+				"cause the the filesystem to be\n"
+				"inconsistent.\n"), stderr);
+			exit(1);
+		}
+	}
 
 	if (sb->s_rev_level == EXT2_GOOD_OLD_REV &&
 	    (sb->s_feature_compat || sb->s_feature_ro_compat ||